Machine tool control



March 9, 1948. J HORNFECK 2,437,603

MACHINE TOOL CONTROL Filed Dec. 18, 1943 5 Sheets-Sheet l 3nncntor ANTHONY J. HORNFECK March 9, 1948.

A. J. HORNFECK 2,437,603

MACHINE TOOL CONTROL Filed Dec. 18, 1943 5 Sheets-Sheet 2 PILOT VALVE FIG. 4 POSITION .0005 .OOI .002 .003 .004 .005

TRACER MOVEMENT INCHES BIAS DO. I I

FIG. 9

FIG. 5

3nventor OUTPUT VOLTAGE ANTHONY J. HORNFECK attorney March 9, A J. HQRNFECK 2,437,603

MACHINE TOOL CONTROL Filed Dec. 18, 1945 5 Sheets-Sheet s Imocntor ANTHONY J. HORNFECK EH60? 1 a d attorney March 9, 1948. A. J. HORNFECK 2,437,603

MACHINE TOOL CONTROL Filed Dec. 18, 1943 5 Sheets-Sheet 4 3nncutor ANTHONY J. HORNFECK FIG 8 '37 JAQM Gttorncg March 9, 1948. A. J. HORNFECK MACHINE TOOL CONTROL Filed Dec. 18, 1945 5 Sheets-Sheet 5 IOI FIG.

FIG.

m UK g F N R O H Y N o H T N A (Ittorneg Patented Mar. '9,

UNITED STATES PATENT OFFICE MACHINE TOOL CONTROL tion oi Delaware Application December 18, 1943, Serial No. 514,786

2 Claims.

. 1 This invention relates to contour control, or duplicators as they are sometimes called, for machine tools such as lathes, shapers, planers, milling machines, die sinking machines, and the like.

An object of my invention is to provide a contour control wherein the desired contour or shape is accurately produced on a work piece, thereafter requiring a minimum of hand finishing.

Still another object of my invention is to provide a contour control or duplicator which may be readily applied to a wide variety of machine tools.

Another object of my invention is to provide a duplicator wherein the linear cutting speed of the tool relative to the work is maintained constant, or is varied in predetermined manner.

Further objects will be apparent from the description and drawings, in which:

Fig. 1 is a plan View of an engine lathe illustrating one application of my invention thereto.

Fig. 2 is an electric and hydraulic circuit diagram of my contour control embodied in the lathe of Fig. l.

Fig. 3 shows a modification of a portion of Fig. 2.

Fig. 4 is a graph of operation of Figs. 1 and 2.

Fig. 5 is a graph of Voltages in connection with Fig. 2.

Fig. 6 is another embodiment of my invention as depicted in an improved electric circuit.

Fig. 7 is a further electric circuit diagrammatically illustrating an embodiment of my invention.

Fig. 8 is an electric circuit for a two-element contour control of a metal working machine.

Fig. 9 is a graph of values in connection with Fig. 8.

Fig. 10 is a modification of a part of the lathe of Fig. 1.

Fig. 11 illustrates my invention as applied to a milling machine.

Fig. 12 is a partial elevation of Fig. 11.

As is well understood by those familiar with the art, in some machine tools, such as lathes, the tool is moved longitudinally and transversely of the work piece which, except for rotation about its center, remains stationary. In other machine tools, such as some types of milling machines, the work piece may be moved in two directions while the tool, except for rotation about its axis, remains stationary. In some other types of milling machines and in some die sinking machines the tool may be moved in one, two or three directions and the work piece also may be moved in one or more directions. In all instances it will be observed, however, that it is the relative movement between the tool and work piece that causes the work piece to be formed to a desired shape.

As one specific embodiment I have chosen to illustrate and describe my invention as incor- 5 porated in a lathe wherein the work piece, except for rotation about its center, remains stationary and the tool is moved transversely and longitudinally thereof. As another specific embodiment I have illustrated my invention as applied to a milling machine wherein the tool, except for rotation about its center, remains stationary and the work piece is moved in two directions in order that the tool may cut the work piece to a desired shape. It will thus be evident that my invention is applicable to a wide variety of machine tools or metal forming machines and that when I speak of relative movement between the tool and work piece I include either an arrangement where the tool is stationary and the work piece moves, or where the work piece is stationary and the tool is moved, or a combination of the two.

Referring to Fig. i, I show my invention applied to an engine lathe l, having a head stock 2 adapted to be rotated by any suitable means (not shown) and a tail stock 3. A carriage 4 is mov=- able longitudinally along the bed of the lathe in suitable ways 5 and supports the tail stock 3. Also movable longitudinally along the bed or the lathe, in suitable ways is a carriage 1 upon 39 which is mounted a cross-slide 8 movable on ways transversely of the bed of the lathe.

The cross-slide 8 is provided with an adjustable tool support 9 in which is secured a tool i0. Transverse movements of the tool ID are produced through the agency of a hydraulic cylinder l I having a piston l2 adapted to position the crossslide 8 through the agency of a piston rod l3. Longitudinal movements of the tool 10, that is movements of the tool parallel to the bed of the 40 lathe in a longitudinal direction, are produced by means of a hydraulic cylinder l4 having an operating piston rod l5.

Supported by the head stock 2 and the tail stock 3 is a work piece It which, for illustrative purposes, is shown as being formed to a parabolic shape by the tool Ill. The particular shape has no significance, it being apparent as thedescription proceeds that by my invention a work piece may be formed automatically to any desired contour. A master template or cam I1 is rigidly held in parallelism to the work piece l6 upon any convenient extension [8 of the lathe bed. The profile of the master i1 is the contour which I desire to reproduce upon the work piece Hi. In

5 Fig. 1 the taper of the work piece It follows in general a, parabolic. function merely as an exam- The tracer assembly I! is shown in larger, more diagrammatic fashion in Fig. 2 as having a pivoted bell crank 20, the end of the vertical arm continually contacting the front edge or profile oi the master template ll. From the horizontally extending arm is freely suspended a metallic core piece 2| positioned relative three windings 22, 23 and 24. It will be apparent that the magnetic coupling between the primary coil 22 and the secondary coils 23, 24 depends upon the relative position or the magnetic core piece 2|, and consequently upon the position of the tracer arm 20., The electric circuit including the windings 23, 24 is energized inductively from the primary circuit and in amount depending upon the magnetic coupling between the circuits. The assembly comprising the windings 22, 23 and 24 along with the magnetic core piece 2| may be constructed as described and claimed in my copending application Serial No. 453,489, and now abandoned.

Energization of the primary winding 22, from an alternating current source, induces a voltage in the windings 23, 24 (which are oppositely wound in bucking relation) to give the core 2| a position corresponding to zero potential through direction an increasing voltage of opposite phase is increasingly eflective upon the tube 28. This results in either an increase in current flow through the tube '26, or a decrease in current flow, relative to the neutral or normal current flow therethrough.

The arm 3|, movable relative to the resistance 32, provides a sensitivity control varying the slope of the curves of Fig. 4, which are graphs of position of the solenoid cores 33, 34 relative to movement of the tracerarm and oi the core 2|. Thus, for example, curve A shows a total travel of the cores 33, 34 for a total movement of the tracer arm 20 of .0005 inch for example. Curve C, for example, is representative of a diflerent relative position of the elements 3|, 32 wherein the output circuit including the windings 23, 24,

the windings 23, 24; with the system so biased that normally a flow of current through the Power tube 28 is opposed b the biasing efiect of the springs 29 and 38,

Referring to the graph of Fig. 5 it will be observed that if E1 and E2 are the voltage curves of the windings 23, 24, then when the plunger 2| is at its mechanical neutral the value of E1-Ez=0 output voltage and E2--E1=0 output voltage. As the plunger 2| moves to the right (Fig. 5) the value of E1 increases while the value of E2 decreases and the value of E1-E2 increases along a substantially straight line as indicated in the lower graph. If the plunger 2| is moved to the left the reverse is true and E2-E1 gradually in creases along a substantially straight line.

As the plunger 2| moves through its mechanl cal and electrical neutral position it will be observed that the output voltage of the circuit in-. cluding windings .23 and 24 reverses in phase. The system is phase sensitive and current flow through the power tube 26 is increased above or decreased below a normal flow, which is so chosen as to offset the biasing action of the springs 29, 30 for desired neutral or normal position. When the plunger 2| is at the mechanical and electrical neutral position, the current flow through the power tube is at some normal value, overcoming, through the agency of the solenoid windings 21, 28, the biasing action of the springs 29, 30. If

the plunger 2| moves increasingly into the. field total travel of the solenoid cores 33, 34 is accomplished through a travel of the tracer arm 22 of approximately .005 inch. Thus the relative position of the elements 3|, 32 provides a sensitivity adjustment between travel of the tracer arm 20 and travel of the solenoid cores 33. 34.

The adjustable arm 35 and resistance 36 provide an adjustable bias to control the neutral position of the solenoid cores 33, 33, i. e, the value of current flow through the output circuit at zero phase across 23, 24. In other words, to determine the current flow through the output circuit of the power tube 26 including the solenoid coils 2?, 28 at time of balanced phase relation across the windings 23, 24 resulting in neutral control of the power tube 25. This is not to be confused with the voltage values of Fig. 5, which are of the control or input circuit of the power tube 22.

The electrical control of the output circuit of the tube 26, namely, control by the elements 35, 36, could be duplicated by adjustment of the spring tension of the springs 29, 32, or by a combination of the two. It is in efiect a control of the biasing of the elements 33, 34 at what may be termed the neutral or normal position of the tracer i9.

For control of the hydraulic motor i I provide an oil pilot valve 37, whose movable element is positioned by and with the solenoid core 33 against the bias of the spring 29 and under the influence of the solenoid winding 27. For positioning of the hydraulic motor i4, I provide a variable fiuid resistance 38 whose movable element is positioned by and with the solenoid core 34 against the bias of the spring 39 and under the influence of the solenoid winding 23. The pilot valve 31 and the adjustable fluid resistance 38 may be of the type disclosed and claimed in the copending application of Clarence Johnson, Serial No. 384,375, now Patent No. 2,372,426, granted March 27, 1945,

I show an oil pump 39 driven by a motor 40 and drawing its supply of oil from a. sump 4|. Oil under pressure is supplied the pilot valve 3? by the pump 39 through a pipe 42. From the pilot 3'! oil is supplied to one end or the other of the hydraulic motor I! through the pipes 43 or 44. Drainage from the pilot 3! is returned to the sump 4| through a pipe 45.

In connection with the hydraulic motor I4 and adjustable resistance 38 I provide switching valves 46, 41 arranged to be moved together to either a normal or a rapid traverse position of operation of the motor M. The valves 46, 41 are shown in Fig. 2 in the normal operating position. Oil under pressure from the pump 39 is forced through the pipe 48, the valve 41, and the pipe 50, to one end of the hydraulic motor I4. Oil from the other end of the motor passes through a pipe 49, the valve 41, the valve 46, the

' hand end of the hydraulic motor l4.

In Fig. 3 I show the passage relation of the switching valves 46, 41 for a rapid return of the piston rod I5 from left to right in Fig. 2. That is, for a rapid return of the tool In to the beginning of its working travel. In such position of the valves 46, 41 oil from the pump 39 passes directly through the pipe 48, the valve 41, and the pipe 43; while oil from the right-hand end of the motor l4 passes directly through the pipe 50, the I valve 41, the valve 46 to the pipe 52 and sump 4|. Thus on the rapid return of the piston rod |5 there is no throttling of its speed of travel by the variable resistance 38, and thus the tool is traversed to the right at maximum speed.

In general the operation of the system illustrated in Figs. 1, 2 and 3 is as follows. If the contacted edge of the master template I1 is parallel to the axis of the work piece l6, then the tracer core 2| is in a normal or neutral position. corre-' sponding to that illustrated in Fig. 5, and resulting in zero output voltage through the intermediate circuit including the windings 23, 24. Under this condition a selected normal current flow exists through the output circuit including the power tube 26 and the solenoid windings 21, 28 exerting such counter-pull against the biasing springs 25, 30 as to position the core pieces 33, 34 and the movable elements of the assemblies 31, 38 to a normal or neutral position. Under this condition the pilot valve 31 locks oil from the pipes 43, 44 so that the piston rod I3 is not moving and the tool l0 travels a cutting path parallel to the axis of the work piece Is. At the same time the variable restriction 38 is in position to provide a normal speed of travel of the piston rod |5 from right to left on the drawing, thus moving the tool l0 along the work at a uniform normal speed.

Ii the profile of the cam l1 recedes from the axis of the work piece, or advances toward the axis of the work piece, the core 2| is correspondingly positioned relative to the windings 23, 24 in proper direction to either increase or decrease the current flow through the windings 21, 28, and cause the core pieces 33, 34 to move upwardly or downwardly as illustrated on the drawing. Such movement causes the hydraulic motor I to position the tool I0 toward or away from the axis of the work piece l6, and thus reproduce upon the work piece It the contour of the master template I 1. At the same time any departure of the movable element of the variable resistance 38 in either direction from normal position will increase the resistance to oil fiow therethrough and tend to slow up travel of the piston rod |5. Under this condition longitudinal travel of the tool In from right to left on the drawing will be at a speed slower than the normal speed, depending upon the rate of travel of the 'tool I0 toward or away from the axis of the work piece l6. If, for example, the profile of the cam |1 includes a shoulder at right angles to parallelism with the axis of the work piece l6, then there will be a complete stoppage of longitudinal travel of the tool III while the tool is advancing directly toward the axis of the work piece or receding directly therefrom. In this manner a right angle shoulder may be cut on the work piece IS without the tool 0 traveling longitudinally relative to the axis of the work piece. It will be observed that movement of the core piece 2|, either upwardly or downwardly on the drawing relative to the windings 23, 24, from a neutral or normal position, results in a decrease of speed of travel of the tool ID in a longitudinal direction from its normal speed of longitudinal travel.

After complete travel of the tool has been accomplished from right to left, then a rapid return of the tool I0 to the right may be accomplished by moving the switching valves 46, 41 to the position shown in Fig. 3 wherein the variable restriction 38 is made non-eifective upon the hydraulic motor l4.

The system which I have just described in connection with Figs. 1-5 inclusive, is in general a two-element control wherein the lathe tool is positioned both transversely and longitudinally of the work piece. It will, of course, be seen that either element may be employed without necessarily employing the second element. For example, a lathe or similar material forming machine .may have the tracer assembly control only they cross feed of the tool or only the longitudinal feed of the tool, or the two combined as previously described. Furthermore, it may in certain instances be desirable to include a third element,

namely, a control of speed of rotation of the work piece It so that the linear cutting speed of the tool will remain constant regardless of the diameter of the work piece at which it is cutting. In other words, so that the speed of rotation of the work piece I8 will be different when the tool I0 is cutting on a large diameter than it is when the tool is cutting on a smaller diameter. To i lustrate such a. possibility I have indicated on Fig. 1 an oil motor 53 for rotating the work l6 and under the control of a tracer assembly ISA (Fig. 10) which may be mounted on and longitudinally carried by the carriage 1 with the tool and cross-slide 8.

On the cross-slide 8 I locate a cam surface 54 movable with the tool Ill and relative to the tracer arm |9A so that the tracer arm |9A is deflected by the cam 54 an amount indicative of the transverse position of the tool H3 relative to the axis of the work piece l5. As explained in connection with Fig. 2, the tracer assembly ISA may control a variable oil restriction such as shown at 38 in an oil supply line leading from the pump 39 t0 the motor 53, or in the discharge between the motor 53 and the sump 4|, so that the speed of the motor 53 will depend entirely upon the position of the core 2| relative to the windings 22, 23, 24, and consequently will depend upon the deflection of the tracer arm |9A with reference to the cam surface 54. In. other words, as the diameter at which the tool Ill is cutting increases or d creases the speed of rotation of the work piece I 6 will correspondingly decrease or increase respectively. It will be apparent that this third element of control may be incorporated on the lathe of Fig. 1 and Fig. 2 either alone or in combination with either or both of the two elements of transverse and longitudinal tool travel.

In Fig. 6 I illustrate an embodiment of my invention wherein the oil pilot valve 31 and the variable restriction 38 are jointly and simultaneously positioned by a capacitor-run type of alternating current motor 55. The motor 55 is also adapted to position .a contact arm 56 relative to a potentiometer 51 for a partial balancing of the electrical circuit following an unbalance thereof.

The electrical arrangement comprises a mutual inductor potentiometer bridge circuit wherein the tracer assembly I!) includes-a3-coil mutual inductor 22, 23A, 24A. The bridge circuit includes a potentiometer or resistance winding 51 divided into two portions by the movable contact arm 56 and hand adjustable resistances 58, 59. It will be observed that the bridge including the windings 23A, 24A and resistances 51, 58 and 59 is not a conventional bridge to which a source of power is directly applied. The power supply is obtained through the magnetic coupling of core piece 2| between the primary energized winding 22 and the secondary windings 23A, 24A. In a steady state of bridge balance the core piece 2| is in the neutral or normal position. Displacement of the core piece 2| in one direction or the other unbalances the bridge and results ina potential being established in the conjugate conductors 60, 6| whose magnitude is representative of the magnitude of the change in position of the core 2|, while its phase is representative of the sense of change in the position of the core piece 2|. In other words, if the core 2| were moved upwardly, then the potential in the conductors 60, 6| would be of one phase while if the core 2] were moved downwardly the potential in the conductors 6|), 6| would be of opposite phase.

The amplifier 25 is sensitive and responsive to the phase of the'potential in the conductors 66, 6| for control of the motor control tubes 62, 63. Any movement of the core 2| causes an unbalance of the bridge circuit and the direction and extent of unbalance is felt in the conjugate conductor 66, 6| and applied to the amplifier 25, which in a through the winding 61 and is simultaneously through the winding 66 in series with the capacitor 68. Desired, directional rotation of the motor 55 is accomplished by preponderance of saturation in the saturating windings of the reactors 64, 65. Whichever reactor predominates determines the direction of rotation of the motor, while the amount of predominance determines the speed of rotation.

Across the saturating winding of the reactor 64 I have shown a condenser 69. A similar con- =denser is connected across the saturating iwinding of the reactor 65. These condensers smooth out the pulsating direct current from the motor control tubes 62, 63 so that the saturating windings of the reactors receive essentially a smooth direct current. Pulsating direct current from the tubes 62, 63 is half wave rectification and the respective condenser discharges in the time interval between the successive pulsations, thus tending to build up those valleys and tending toward a smooth direct current flow to the saturating windings rather than a definite pulsation or intermittent flow.

point, particularly in obtaining high sensitivity.

The transformer H is an auto transformer having a winding 12 in series with the A.-C. output winding of the reactors 64, 65 so that full voltage will be obtained to operate the motor 55, which is preferably a standard or commercial type of motor. 1

Whenever the profile of the master template I1 is parallel with the axis of the work piece the core 2| will be in its neutral or normal position, and the motor 55 not rotating. The movable elements of the pilot 31 and variable restriction 38 will be in their normal position. Upon a change in the profile of the'cam ll, resulting in a movement of the tracer arm 20 and consequent raising or lowering of the core 2| relative to the windings 23A, 24A, there will be an unbalancing of the bridge circuit, resulting in a potential in the conjugate conductor 60, 6| of a phase depending upon the direction of movement of the element 2| relative to the windings 25A, 25A. Such unbalance of the bridge circuit results in a rotation of motor 55 in direction and at a speed dependent upon the direction of movement of the core 2| and the extent of such movement.

The motor 55, in addition to positioning the movable elements of 37, 38, is also adapted to move the contact arm 56 relative to the potentiometer or resistance 57 for at least a partial balancing of the bridge circuitfollowing an un-. balance thereof. In other words, if the tracer arm 20 moves in one direction or the other, resulting in an unbalance of the bridge circuit and a rotation of the motor 55 then such movement of the motor 55 positions the arm 56 relative to plated that the gearing between the motor 55 and the arm 56 may be so chosen that under certain conditions the motor would not be expected to completely rebalance the circuit, or in other words an insufllcient movement (for rebal-- ancing) of the contact arm 56 would be accomplished. The remaining balancing (simultaneously with the movement of the arm 56) would be accomplished by movement of ,the tracer assembly l9 relative to the template ll. Such movement of the assembly I9 is, of course, accomplished by movement of the tool in and crossslide 8 on which the tracer assembly i9 is mounted. However, a partial rebalancing of the bridge circuit by the motor 55 would tend to prevent hunting or overtravel in case of sudden drastic changes in the profile of the template H.

In Fig. '7. I show a further embodiment of my invention in a balanceable circuit energized inductively from a primary winding 22 and a similar primary winding 22A. The secondary circuit includes windings 23, 24 and l5, l6 in loop connected by conductors I3, 14. Conductor id includes an amplifier 25A for control of a motor 55A. The motor 55A is shown as being of the type'having a field winding 11 energized from a suitable source of alternating current, and opposed shading pole windings 18, I9. When the windings 18 and 19 are open circuited or are both effectively short circuited the motor 55A remains stationary. When the pole winding 18 is effectively energized as by being short'circuited, the motor 55A will rotate in one direction and when the winding 19 is efiectively energized as by being short circuited the motorjA will rotate in opposite direction. I In order that a voltage of one phase in the conductor" will cause, for example, efiectlve short circuiting of the pole winding 18 and a voltage of reverse phase will cause effective short circuiting of the winding 19, I employ an amplifying and control'circuit between the conductor 14 and the motor 55 forming the subject matter of Patent 2,275,317 to John D. Ryder:

The voltage existing across the conductor 14 is first amplified by means of an electron. discharge device 80 having a cathode 8|, a grid 82,

and an anode 83. The voltage between the terminals 84, 85 controls the potential relationship between the cathode 8| and grid 82. Theplate circuit of the electron discharge device 88 includes a resistance 86 and a source of direct current 81. When the potential difference between the terminals 84, 85 is zero a direct current may or may not pass through the plate circuit of the device 88 depending upon the electrical characteristics of the device and the bias of the grid 82.

An alternating current voltage between the terminals 84, 85 superimposes, upon the normal grid bias of the device 88 a pulsating control potential which causes the current in the output circuit of the device 88 to become similarly pulsating in character. The amplitude of the pulsations in the output circuit will depend upon the difference in potential of the terminals 84 and 85 while the phase of the pulsations will depend upon Whether the potential at the terminal 84 is greater or lesser than that at the terminal 85. The output is utilized to control the current transmission through, a second pair of electron discharge devices 88 and 89, the output circuits of which are inductively coupled through transformers 98 and 9| to the circuits of the pole windings I8 and 19 respectively. Such direct current as may normally flow through the output circuit of the device 80 will have no effect upon the potential impressed upon the grids of the devices 88 and 89 by virtue of a condenser 92. Upon an alternating current voltage existing between the terminals 84 and 85 however the pulsating component of the current in the output circuit of the device 88 will pass through the condenser 92 and render either the device 88 or the device 89 conducting selectively in accordance with the phase of the voltage between the terminals 84 and 85.

Such selective control of the devices 88 and 89 is obtained by arranging them to have opposite polarity. That is, when the anode of the device 88 is positive, the anode of the device 89 is negative, and vice versa. As hereinbefore stated, the phase of the pulsating current in the output circuitv of the device 80 will depend upon whether the potential of the terminal 84 is greater or lesser than at the terminal 85. Accordingly, upon the potential at the terminal 84 being greater than that at the terminal 85 pulsating current in the output circuit of the device 80 may render, for example, the grid of the device 88 more positive with respect to its cathode during the same half cycle that its anode is positive, and hence rent in the output circuit of the device 80 will be in phase with the plate potential oi. the device 88, and hence will renderthe grid thereof more positive with respect to its cathode during the same half cycle that its anode is positive, so that the device will be rendered conducting.

When either the device 88' or 89 is rendered conducting, thereby effectively short circuiting the secondary of the transformer 80 or 9| respectively, the impedance of the circuit of the pole windings 18 or 19 is sufficiently reduced to effect rotation of the motor A in one direction or the other. Such rotation positions the pilot 3! and the variable restriction 38 and simultaneously positions a core piece 2 IA relative to the windings l5, 16 to again make the potential induced in the windings 1'5, 16 equal to that induced by the 'winding 22 and the windings 23, 24. Thus movement ofthe motor 55A tends to rebalance the electrical network, following an unbalance thereof, simultaneously with movement of the tracer assembly I 9 relative to the template IT for repositioning the core 2| to its normal or neutral position.

In Fig. 8 I show an embodiment oi. my invention wherein the capacitor-run alternating current motor 553 is not used to position a pilot 31 or variable restriction 38, but may be connected directly through the necessary gear reduction and lead screw to position the cross-slide 8 and tool |8 toward or away from the work piece l6. Simultaneously a capacitor-run motor 55C is utilized for traveling the tool l8 longitudinally of the work piece l6 at a variable speed and with provision for rapid return of the tool to its starting point.

The electric circuit control ef the motor 553 is substantially as described in connection with the motor 55 of Fig. 6. At the outlet of the amplifier 25 I have taken a parallel connection ofi for control of'motor tubes 93, 94 in circuit with the motor 55C. The tubes 93, 94 are phase sensitive and are so biased that if the core 2| moves out of its neutral position in one direction, then the tube 93 is turned on, and if it moves out of neutral in the other direction then the tube 94 is turned on. At neutral position of the tracer core 2| both tubes are turned off and IA and I are zero (Fig. 9), As the core 2| departs from neutral in one direction the current IA increases toa maximum, and if the core 2| departs from neutral in the other direction the current In increases to a maximum. This is clearly shown in Fig. 9. V

In the output circuits of the tubes 93, 94 is the saturating winding 95 of a saturable core reactor 96 having a bias direct current saturating winding 91 provided with adjustable means 98. The reactor 96 has an alternating current output winding 99 connected through the double-pole double-throw switch I88 to energize the motor 550.

The saturable core reactor 96 is continuously biased by the direct current saturating winding 91 to an extent of greater magnetism than the saturation effect ever reached by the winding 95 through the action of either the tube 93 or the tube 94. This is shown in Fig. 9. Thus at neutral position of the core 2| the current flow through the saturating winding 95 is zero and that through the bias winding 91 is maximum. Under these conditions of minimum impedance through the winding 99 the motor 550 rotates in one directton at maximum speed for longitudinal travel of the tool I8 along the work piece l8. As core 2I moves away from neutral in either direction the current flow (In or In) increases from zero, through the winding always in the same direction, and opposing or counteracting the eflect of the bias saturating winding 91. At maximum displacement of the core 2| the bias winding saturation is nearly overcome and the motor 556 ceases to rotate and the longitudinal travel of the tool I0is stopped.

It is to be noted that regardless of the direction oi! deviation of the core 21 from neutral position the speed of the motor 550 is always in the same rent power source in such manner as to run it at looking down on av vertical milling machine having a column .IOI, a work table I02 and a rotatable form milling cutter I03. The work table I02 is carried on a saddle I I3 mounted-on horizontal guideways I04 carried by a knee I05 which is supported in vertical guideways I 06 formed on the column IN. The cutter I03 while rotating is nor; mally in fixed axial position. The work table I02 rotates and is movable horizontally along the guideways I01.

At I08 is shown a typical work piece consistin of a concave forging of more or less elliptical shape and in rough form having a raised blank face extending around its entire periphery. The machining operation which I have chosen as illustrating my invention includes forming a male flange face on this blank. The cutter I03 is suitably shaped to relieve the outer edge of the flange.

. 1.2 ment I9 having its tracer arm 20 engaging the periphery oi. the cam III. The device I9 controls the hydraulic motor II drivin the piston rod I2 for horizontally positioning the work table I02 along the guides I0'I on the saddle I I3.

In Fig. 12 I show an elevation of a portion of the milling machine of Fig. 11. I provide a second cam or template I I4 rotatable with the work table I02, the work I08 and the cam I I I. En a ing the cam I I4 is the contact arm 20D of a tracer ISD mounted on the non-rotatable portion of the work table I02. The tracer I9D is, however, movable along the ways I0'I of the saddle II3 with the rotatable and the non-rotatable portion of the work table.

A motor similar to the motor 53 for rotating the rotatable portion of the work table I02 is movable along the ways I01 with the entire work table assembly. This motor is controlled by the tracer I9D in engagement with the cam IM and functions to provide a speed oi. rotation of the work piece dependent upon the cam profile I Id.

In general, the arrangement is such that the cam III provides for transverse movement of the work I08 relative to the cutter I03, and while v the work I08 is making one complete revolution. The cam I-Id functions to determine the speed .of rotation of the work piece I08 relative to the cutter I03 during the single revolution of the work piece. The hydraulic motors II and 53 under the control of the tracer assemblies I0 and 'I9D respectively may be of the type described and controlled as described. In other words, the hydraulic motor iI is adapted to position the work table assembly back and forth relative to the cutter I03 and at a variable speed. The

and by my invention the rotating work piece is automatically moved along the guideways I01, relative to the cutter I03, so that the latter accurately forms the outer profile of the raised portion of the flange.

The work piece I08 is shown as being secured to a fixture I00 by adjustable clamping means I I0. Because of the nature of the machining operation to be performed, the fixture I09 is secured to the work table I02 and is rotated at desired speed by a hydraulic motor similar to the one designated 53 in Fig. 1 and controlled in a manner described in connection therewith. In other words, the rotation of the table I02 may be at a variable speed dependent upon the particular shape of the contour to be produced. Machining of the work piece I08 is completed in one revolution of the work table I02; the work piece being moved relative to the cutter I03 to accurately profile the male flange by means-now to be described.

The fixture I09 has a horizontally extending skirt III forming a cam or template, the contour of which is formed to produce the desired contour of the raised portion of the flange on the work piece I08. A raised barrier I I2 is preferably employed to hold chips cut from the work piece from scattering.

Supported by the saddle H3 is the tracer elemotor 53 rotates the work always in one direction but at a speed dependent upon the contour of the cam I I0.

While I have chosen to describe certain preferred embodiments of my invention, namely, in connection with a lathe or a milling machine, it

will be understood that I am not to be limited thereto but that my invention is equally applicable toany metal forming machine where it is desired to shape a work piece to the configuration of a master cam or template by relatively moving the tool or work piece.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a material forming machine having a relatively movable tool and work piece, a pair of capacitor-run motors for effecting relative movement of said tool and work piece simultaneously in angularly related paths, a pattern having the desired shape of the work piece, a tracer mechanism scanning the pattern as the tool traverses the work piece and adapted when displaced to effect a change in an electrical characteristic in opposite directions from a normal, and an electric network including the motors and tracer, said network including a source of alternating current, a pair of saturable core reactors connected to regulate current from said source for directional speed control of one of the motors and a single saturable core reactor connected to regulate current for speed control only of the other motor, both said pair and said single reactors having cores, and means to variably saturate said cores in accordance with the characteristic change from normal.

2. In combination, an alternating current electric motor, a network for controlling the speed of rotation of said motor including, a saturable core reactor having an alternating current winding connected to control current flow to said motor for speed control thereof and having two direct current saturating windings in bucking relation to each other, said saturating windings being termed a control winding and a bias winding, a hand adjustable supply of direct current for the bias winding which at maximum alone would cause the motor to rotate at a selected maximum speed, a source of direct current for the control winding, means sensitive to changes in a variable in either direction from a normal for always increasing the current flow in the said control winding upon increase or decrease in the variable from said normal to a limit in saturating effect always below the saturating effect of the bias winding whereby upon deviation of the variable from normal the motor speed is always decreased and in amount dependent upon the amount of deviation of the variable in either direction from normal.

ANTHONY J. HORNFECK.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,921,983 Whittkuhns Aug. 8, 1933 2,116,593 Bouvier et al May 10, 1938 2,150,032 Herman et a1. Mar. 7, 1939 2,226,677 Vikhman Dec. 31, 1940 2,228,902 Allen 1. Jan. 14, 1941 2,245,894 Arms June 17, 1941 2,259,472 Johnson Oct. 21, 1941 2,275,317 Ryder Mar. 3, 1942 2,310,955 Hornfeck Feb. 16, 1943 2,313,989 Caldwell et al. Mar. 16, 1943 

